Building the tap tempo tremolo

JKowalski · May 09, 2011, 05:39:10 PM

Quote from: Barcode80 on May 05, 2011, 06:09:11 PM
Quote from: Geosh on May 05, 2011, 02:11:14 PM
Can someone give me a good recommendation for a switch for the tap tempo? The one I have now is very finicky and doesn't seem to lock in well with my taps. It seems to not recognize some and sometimes tapping at 60bpm produces a 6000bpm result (exaggerating... but only a little). Should it be a normally open switch? Supplier and part number would be appreciated.
Thanks!
Mine does that occasionally. It's a debounce issue I can't seem to track down. It's rare enough it never bothers me though.

Put a small value capacitor across the tap switch terminals, maybe 10-100nF. The debounce is done in code but may be finicky for switches with extremely long bounce.

If that doesn't help then a new switch is a good solution. Yes, it should be a normally open switch. I can't suggest a good switch, I haven't had experience with many. Maybe someone who has a large stock of different switches can do a bounce-time shootout?

Quote from: Jimi W on May 01, 2011, 08:23:01 AM
Hi Taylor,
Thanks for the reply. I actually understand the long explanation in terms of the voltage divider. Alarm bells did ring when you mentioned a 25K resistor and it dawned on me I would've altered the total resistance of the chain and therefore the voltage divider.

Its working perfectly now and my wife and baby have been out this morning so I've given it a good play through a cranked amp. Great pedal. I really like the multiplier footswitch. I think it would be really useful in a live situation and allow a bit more creativity without needing to tweak knobs. Shame I'm not in a band anymore!

I'd be even better if I could get the status LE D's of the multiplier Rotary switch to change as I stepped through as a visual reference. Is the stepping through done completely within the chip and is there no way to get the voltage and use it to drive a LM3914? I've measured the voltage on the multiplier pin (pin 11 if I remember rightly) and it doesn't change when your step through the multipliers. I'm guessing its not possible.

Cheers,
Jim

Yes stepping is done in code, no outputs from the chip currently have any information on that particular setting. Sorry, that part of the code was organized as a "theres an extra pin on the chip, let's try to put something in!" kind of deal. A johnson counter would not work well because it would go out of sync all the time, with the way the code works.

EDIT: Well, there is a way but it would be pretty complicated. It involves using the multiplier pin voltage as a reference and a weighted johnson counter to incrementally add to the voltage input to the LM3914 you are using.

azrael · May 15, 2011, 11:41:11 AM

Would there be no problems if I used one of these:

connected the Tempo pot to the three lugs, and then let the pot be disconnected when there was a stereo cable plugged, allowing an expression pedal to be used in place of the Rate/Tempo control?

G. Hoffman · May 17, 2011, 06:42:09 PM

Any idea, Taylor, when these might be back in stock?

Gabriel

Valoosj · May 18, 2011, 12:00:00 PM

I'm not sure if anyone ever made a demo of this pedal, so here's mine

alfafalfa · June 07, 2011, 01:21:51 PM

Sounds good Yorick but I'm very interested in the sine wave sound and I missed that in your demo.

Could you perhaps tape a small part with that sound , would be really great !

Tia,

Alf ( from Holland !)

Taylor · June 07, 2011, 01:31:12 PM

Quote from: G. Hoffman on May 17, 2011, 06:42:09 PM
Any idea, Taylor, when these might be back in stock?

Gabriel

Hi Gabriel, the tap tempo tremolo PCB is back in stock as of today.

Valoosj · June 08, 2011, 03:06:52 PM

Quote from: alfafalfa on June 07, 2011, 01:21:51 PM
Sounds good Yorick but I'm very interested in the sine wave sound and I missed that in your demo.

Could you perhaps tape a small part with that sound , would be really great !

Tia,

Alf ( from Holland !)

From 3:40 all the way til the end it is on sine wave.

alfafalfa · June 09, 2011, 11:00:30 AM

Thanks, you're right of course but what I really mean is a part where what you play is in sync with the tremelo speed.
I'm looking for an old fashioned slow sinus tremelo sound. My tremulous lune sounds okay but it hasn't what I'm after.

"That's the way" from Venice is the sound I'm looking for.

Valoosj · June 11, 2011, 03:31:56 PM

Since a few days ago I am no longer able to select a waveform. The pedal worked just fine before. I opened it up and measured 7,5V at my 78L05. Is it safe to assume that it is busted and in need of replacement? I had a chance to measure the one which I made for a friend, and there I had 6V at the 78L05. That pedal works fine.
Should I search for a better supplier for the 78L05, or is this normal?
Is there anything I can do to prevent blowing this transistor?

.Mike · June 11, 2011, 03:40:30 PM

According to the datasheet on the 78L05, if you feed it 7-20 volts and pull a current of 1-40 mA, the output should be between 4.75 and 5.25 volts. I just don't see any circumstances where the tap tempo tremolo circuit would exceed the input voltage or current draw.

I'd say something is up with either your regulators, or your builds.

When I was breadboarding the TAPLFO a couple of months ago, I swear had some regulators whose pinouts were opposite of what it shows in the datasheet. In particular, I think they were 5v regulators from Tayda, but I'm not sure. They put out well over 5v until I turned them around.

Grab your breadboard, a regulator, and your multimeter. Make sure you have them oriented correctly.

Mike

Valoosj · June 11, 2011, 05:26:58 PM

I'll give that a go then. Hopefully this is the case as it would be an easy fix.

Skruffyhound · June 12, 2011, 05:15:34 PM

The 7805 and 78L05 are opposite pinouts IIRC, that tripped me up a few times. I don't know if that's adding to the confusion.

Valoosj · June 13, 2011, 01:06:39 PM

That's what I missed, I just had a butcher's at my layout and the pinout is incorrect there. Thanks for clearing this up guys. Would have found it out, but haven't had the chance to look at the pinout and such.

1878 · June 26, 2011, 04:12:16 AM

Yesterday was a good day.

Amongst other things, I finished the TTT. It's fantastic !! Worked first time, no ticking and a really versatile effect. I would suggest having an external gain pot to anyone thinking about building it. It can get a bit quiet with narrow pulse widths.

Pics to come soon.

Thanks Taylor !!

azrael · July 15, 2011, 03:08:34 PM

hey guys, got a bit of an issue here. With the waveform knob, I'm not getting a random waveform at the end of the taper. the effect just shuts off. thoughts?

got a bit of ticking, dialed it out, but the level seems kind of low. might have to change the gain trimpot so I can get it up to line level!

Taylor · July 15, 2011, 05:03:22 PM

When you say it shuts off, do you mean your signal comes through unaffected or the signal cuts out?

azrael · July 15, 2011, 10:01:54 PM

Signal cuts out, pulsing LED turns off.

Also sometimes the tap function is weird and oscillates.

.Mike · July 15, 2011, 10:08:37 PM

What voltage is the waveform pot putting out at the end of the taper?

karter2000 · July 16, 2011, 01:50:52 AM

Just finished mine (no box, but working). It sounds great to me, as everything sounds like it's working. No ticking, even with the trimpots turned up. I used a 2.2nF in place of the 330pF, and used an NSL-32. The tap function is awesome!! I'm batting 3-0 with Taylor's projects!

azrael · July 17, 2011, 03:47:52 PM

Quote from: .Mike on July 15, 2011, 10:08:37 PM
What voltage is the waveform pot putting out at the end of the taper?

Itt's kind of hard to tell. All i know is that the taper of the waveform pot pretty different from the last Tremolo I built, that one had no problems.

The only parts substitution I made was a 470pF cap instead of 330pF.

Oh, and I "made" a 3.6k resistor with two 1.8K.

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Building the tap tempo tremolo